Anti-flash shutter with two compartments

ABSTRACT

In a frame of the shutter an opening is provided for the passage of light, and at least three transparent plates extend across the opening to define with one another two compartments which the light must pass successively. Explosive charges are provided for opaquing both compartments simultaneously to thereby terminate the passage of light through the opening.

United" States Patent 11 1 Friingel et al.

[ 11" 3,836,233 1*Sept. 17, 1974 ANTI-FLASH SHUTTER WITH TWO 5,342,5409/1967 Abegg et al 350/160 R COMPARTMENTS 3,344,434 10/1967 Beckmann eta1....

3,409,909 11/1968 Scott et al 350/160 R 1 lnvemorsi Frank Friingel,Herwigredder a, 3,424,515 l/l969 Risk 2 Hamburg 56; Horst Lohse,3,674,344 7/1972 Lacy Hamburg, both of Germany 3,721,172 3/1973 Frungelet al 350/266 [73] Assignee: said Frungel, by said Lohse m" PrimaryExaminerRona1d L. Wibert Not1ce: The portton of the term of th1s patentsubsequent to March 20, Assmam Examiner-Y MFGraw 1990 has beendisclaimed Attorney, Agent, or Fzrm--M1chael S. Str1ker [22] Filed: Dec.23, 1971 21 Appl. No.: 211,495 [57] ABSTRACT In a frame of the shutteran opening is provided for [30] Foreign A li ati P i it D t the passageof light, and at least three-transparent Dec 24 1970 Germany 2063888plates extend across the opemng to define with one another twocompartments which the light must pass [52] U S Cl 350/266 95/53 350/ Rsuccessively. Explosive charges are provided for 350/2673 opaquing bothcompartments simultaneously to 51 Int. Cl G03b 9/08, G021 1/28 therebyterminate the Passage 0f the [58] Field of Search 350/160 R, 266, 267,312; openmg' [56] UNITE D SEFX F ES EgENTS 20 Claims, 4 Drawing Figures2,489,751 11/1949 Candler, Jr. 350/267 f [111 l I 1 l 1 1 it 5 ];k1u11111 d a V1254 llllllllllll'rl J/:(- '=u 5/ r1111 4 5 PAIENIED3.836.233 sum 2 or 2 1* ANTI-FLASH SHU'l'lER'WITH 'rwo COMPARTMENTSBACKGROUND OF THE INVENTION The present invention relates generally to ashutter, in particular to an anti-flash shutter. Still more particularlythe invention relates on an anti-flash shutter having closure timesshorter than 100 microseconds, which is particularly suited forprotecting the human eye against atomic flash.

Anti-flash shutters of the general type here in question are alreadyknown. Their purpose is to blacken or opaque the shutter cross sectionin a relatively short period of time, for instance by injecting into achamber carbon powder orbe vaporization of electrically detonatablewires or the like. Such shutters are used where a rapid closure (againstpassage of light) of relatively large cross-sectional areas, forinstance on the order of between substantilly 30 and 200 cm is required,which cannot be obtained with the necessary rapidity in any other way.Conventionally, such shutters have a single chamber and are usuallyprovided with a unit composed of a charge of carbon powder and a smallquantity of explosive, for instance nitro-pentane (Np) plus sulfur acidor lead-tricinate. When the explosive is detonated, usuallyelectrically, it blows or injects the charge of carbon powder into thechamber from an edge zone of the latter, thereby opaquing or blackeningthe shutter. It is also known to provide two or more such units spacedcircumferentially of the chamber, in order to obtain shorter opaquingtimes. This means that quantities of carbon powder are blown into thechamber from two or more locations, and this carbon powder usuallyadheres to the inner surfaces of the transparent plates -generallyglasswhich bound the chamber.

It is also known from the prior art to use an explosive wire which, whendetonated, will explosively vaporize with the vaporized material of thewire becoming deposited on the surfaces of the plates and opaquing theshutter in that way. Again, several such wires can be used per chamber.

These prior art constructions are fully usable for many of the intendedapplications. They do, however, have the disadvantage that if they arelocated at a relatively short distance from the site of a nuclearexplosion, they will be destroyed by the heat generated during theexplosion. At the very least, there is a danger that such shutters willbecome damaged under these circumstances and will not operate properly,thereby threatening injury to the eye of a viewer who happens to beusing the shutter at the time the detonation occurs. Attempts have beenmade to overcome the problem by vapor-depositing a layer of gold onthesurfaces of the transparent plates, to act as a heat reflector.Unfortunately, the advantages obtained in this manner by the reflectivecapability of the deposited gold layer are more than overcome by thefact that the deposition of such a layer reduces the visibility throughthe shutter -which normally amounts to between substantially 80 and 90percentto approximately 5 percent. Thus, the deposition of a reflectivegold layer was found not to be the answer to the problem.

SUMMARY OF THE INVENTION It is, accordingly, a general object of thepresent invention to provide an improved anti-flash shutter of the typehere under discussion which is not possessedof the disadvantages of theprior art.

An additional object of the invention is to provide such an improvedanti-flash shutter which is capable of withstanding the heat flashgenerated during a relatively close nuclear explosion.

Another object of the invention is to provide such an improved shutterwhich can be produced inexpensively.

In pursuance of these and other objects which will become apparenthereafter, one feature of the invention resides in an anti-flash shutterwhich, briefly stated, comprises a frame having an opening for thepassage of light, first means extending across said opening and definingat least two axially successive internal compartments through whichlight must pass successively, and third means for terminating thepassage of light through both of said compartments simultaneously.

Such a shutter has the advantage that even if that chamber which facestowards the nuclear explosion is destroyed as a result of the heatflash, the other chamber will remain intact and provide the desiredprotection.

It is advantageous to utilize three substantially parallel transparentplates extending across an opening in the frame, the outer platesdefining with the inner plate the two chambers. The opaquing means maybe located in the region of the center or inner plate, that is in theregion of the circumferential margin of the inner plate, with such meansbeing electrically activatable.

The invention further proposes, according to another concept, that theframe itself be of an elastomeric material which is resilientlyyieldable, and silicon rubber has been found particularly suitable forthis purpose.

The transparent plates themselves may be of synthetic plastic materialbut, depending upon given optical requirements, they may also be made ofglass which may or may not have special optical characteristics. Theutilization of elastomeric material for the frame makes it possible forthe shutter to yield, particularly to yield to the internal pressurewhich will suddenly occur in the chambers when the explosive charges orwires are detonated to blow the carbon powder into the chambers. Thisreduces the possibility that the shutter might become destroyed ordamaged by separation of the margin of the plates from the frame withthe consequent possibility that some or all of the opaquing material(E.G., the carbon powder) might vent to the exterior and prevent properblackening of the shutter.

The opaquing itself, that is the injection of opaquing material intoboth chambers, takes place symmetrically which means that the center ormiddle plate can be made of a different material than the two outerplates. Thus, this material of the center plate need not be resistantagainst shock waves resulting from the detonation of the explosivecharges and can be selected in accordance with other considerations, forinstance it can be a material having good adhesion for carbon powder orother material used for the opaquingcharge, such as the materialavailable under the tradename Ziellon. This is also a reason why theshutter according to the present invention can be made of much lighterweight and of much smaller thickness than would otherwise be possible,considerations which are evidently also important. The fact that theframe can yield makes it also charges, that is the wires which are toconnect the charges with a source of electrical energy for detonatingthem, in the frame itself. In fact, a plug or connector may also beembedded, with the wires connected to it and with suitable male orfemale portions of the connector being exposed at the exterior of theframe for engagement with a similar external connector which in turn isin electrically conductive relationship with a source of electricalenergy. By so embedding the wires and the connector, considerable laboris saved which would otherwise be necessary for installing thesecomponents in proper manner. Also, the charge of carbon powder and theexplosive charge (or charges, if more than one are provided of each) areembedded in the frame so as to be sealed with respect to the outer sidethereof, which eliminates the necessity for providing screw connectorsas in the prior art into which these components are threaded from theexterior.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a cross section through anembodiment according to the present invention;

FIG. 2 is a diagrammatic plan view through a further embodiment of theinvention;

FIG. 3 is a section taken on line III-III of FIG. 2; and

FIG. 4 is a fragmentary section through still another embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing now indetail, and firstly the embodiment illustrated in FIG. 1, it will beseen that the shutter disclosed in the Figure is provided with twospaced, parallel transparent outer plates 1. These plates 1 may be ofsynthetic plastic material or of glass, depending upon the requirementsmade of the, especially optical requirements. If synthetic plasticmaterial is utilized, it may advantageous be polymethylmethacrylate ofthe type which is commercially available under the tradenamePlexiglass," or polycarbonate of the type available under the tradenameMakrolon." Located between the plates 1, in parallelism therewith andspaced from both of them, is an inner or intermediate plate 3, which maybe of a material having particularly good adhesive characteristics (tofacilitate adhering of the carbon powder or the like to it), or whichmay have other desirable characteristics, for instance it may be of amaterial which is especially resistant to thermal energy. Such materialmay for instance be of the type which is commercially available underthe tradename Cellon" from the German "Dynamit" Company. Of course, theplate 3 must be transparent as are the plates 1.

A frame 6 is provided, in this instance composed of elastomeric materialwhich is resiliently yieldable, and silicon rubber with high resilienceis particularly advantageous for this purpose. The plates extend acrossthe opening provided in this frame 6, and in the region of the outercircumferential margin of the plate 3 there are embedded in the frame 6charges 3 of carbon powder in which in turn there are embedded explosivecharges 4 of known type. Reference numeral 5 designates conductors whichare connected with the charges 4, also being embedded and extending tothe exterior of the frame 6 for connection with a source of electricalenergy which is required to detonate the charges 4.

Frame 6 is surrounded at its outer side with a member 7 which is ofsubstantially U-shaped cross section with the open side facing inwardlytowards the frame 6. Member 7 may be of synthetic plastic material or ofmetal and is utilized particularly for relatively largedimensionedshutters, especially if they have a rectangular or quadratic outline. Ifthe member 7 is of metallic material, it can be conductively connectedwith one of the wires 5 whereas the other wire passes out of the frame 6and out of the member 7 via an insulated bushing 9 to provide anexternal contact 8 for connection with a source of electrical energy. 7

It will be appreciated that in place of the charges illustrated in FIG.1, others can be utilized. For instance, it is possible to provide thatchamber which faces towards the light source that is the nuclearflashwith an explosive wire which, when electrically detonated, willexplosively vaporize so that its vaporized particles become deposited onthe plate surfaces binding the chamber in question. The other chamber,that is the one facing away form the light source, can be provided withthe carbon and explosive charges described with respect to FIG. 1. Thisembodiment is insofar advantageous as the vaporized particles of theexplosive wire provide excellent reflective capability in the chamberfacing towards the explosion (that is the nuclear explosion), whereascarbon powder is preferred for the other chamber because it provides fora more definite blackening.

Coming to the embodiment in FIGS. '2 and 3 it will be seen that herethere is illustrated a smaller shutter of circular outline. In suchsmaller shutters, and particularly in shutters of circular outline, themember7 of the embodiment in FIG. 1 may be omitted. This is especiallytrue when the outer transparent plates 11 and the intermediate plate 12are secured together by means of bolts or screws 19 which aredistributed about the circumference of the shutter. The frame 16 isagain of elastomeric material of high yielding capability, and it ispossible but not necessary to locate intermediate the plate 12 and thetwo plates 11 a spacing member or spacing rings in order to locate andmaintain the plates in parallel relationship.

FIGS. 2 and 3 show that a single carbon charge and explosive unit islocated at the frame centrally intermediate the plates 11, so that itcan discharge to both axial sides of the plate 12. Thus, the centralunit discharges into both of the chambers simultaneously and opaquesboth chambers simultaneously. The explosive charge 14 is located againin the carbon powder charge 13 and electrically conductive wires 15 areprovided which extend to the outer side of the frame 16. Of course, asingle unit can be utilized only if the cross section which is to beblackened is not so large that excessive time will be required foreffecting the opaquing. Alternately more than one such unit can beprovided, distributed about the circumference of the shutter.

In the embodiment of FIG. 4 we show that a shutter according to FIG. Ican be constructed in accordance with the opaquing concept of FIGS. 2and 3. In other words, the single unit (or each unit) can act on bothchambers simultaneously to opaque them. In this embodiment the carbonpowder charge 24 has embedded in it the explosive charge 25, being solocated in a frame 26 intermediate the two outer plates 21 that the twochambers, which are defined between the plates 21 by the intermediateplate 22, will both receive carbon powder simultaneously from the charge24.

Shutters of the type here in question frequently must be capable ofstorage for prolonged periods of time. In order to prevent the intrusionof moisture into the carbon powder charge under such circumstances, itis possible to provide on the carbon powder charge a cover, preferablyin the form of a coating of colonium or Zapon lacquer and to therebyseal the charge against the intrusion of moisture. In addition, such acoating prevents falling-out of carbon particles into the chambers, forinstance in case of an impact on the shutter during careless handling orthe like.

In addition, the intrusion of air and moisture can also be visuallysignalled according to a concept of the invention, in that the twochambers are evacuated to an extent sufficient to cause the outer plateto become slightly inwardly deformed in a concave manner. This is trueparticularly in the shutters having plates or synthetic plastic materialand as long as the concavity is visible the user is assured that air andmoisture will not have intruded. On the other hand, if the concavity isnot visible, then the shutter is replaced as no longer absolutelyreliable in its operation.

The assembly of the shutter may be carried out in a manner analogous tothat disclosed in German Pat. No. 1,939,740.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied inanti-flash shutter, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended:

1. An anti-flash shutter, comprising a frame having an opening for thepassage of light; first means extending across said opening and defininga chamber; second means also extending across said opening andsubdividing said chamber into one compartment adapted to face the heatflash of a nuclear explosion and subject to destruction by such flash,and an axially successive additional compartment through which lightmust pass after passing through said one compartment; and third meansfor simultaneously terminating the passage of light through both of saidcompartments so that maximum opaquing of the shutter results upon theoccurrence of a flash and opaquing of at least said additionalcompartment remains even in the event of destruction of said onecompartment.

2. An anti-flash shutter as defined in claim 1, said center plate havinga circumferential margin; and wherein said third means is located in theregion of said margin.

3. An anti-flash shutter as defined in claim I, said first meanscomprising at least two at least substantially parallel transparentouter plates spaced from one another so as to form said chamber, andsaid second means comprising a center plate located between said outerplates.

4. An anti-flash shutter as defined in claim I, wherein said third meanscomprises at least one unit including a charge of carbon powder and anexplosive adapted to discharge said carbon powder into one of saidcompartments, and at least one explosively vaporizable wire adapted todischarge into the other of said compartments and form a reflectivelayer therein.

5. An anti-flash shutter as defined in claim 3, said center plate beingof a material having high thermal resistance.

6. An anti-flash shutter as defined in claim 3, said plates havingcircumferential margins sealingly connected with said frame; and whereinsaid frame is composed at least predominantly of elastomeric materialwhich is resiliently yieldable.

7. An anti-flash shutter as defined in claim 6, wherein said elastomericmaterial is silicone rubber.

8. An anti-flash shutter as defined in claim 6, further comprising anelectrically conductive additive admixed with said elastomeric material.

9. An anti-flash shutter as defined in claim 8, wherein said additive isgraphite.

10. An anti-flash shutter as defined in claim 3, wherein said plates areof synthetic plastic material.

11. An anti-flash shutter as defined in claim 3, said. third means beingelectrically activatable; and further comprising electrical conductormeans and connecting plug means embedded in said frame.

12. An anti-flash shutter as defined in claim 3, said plates havingcircumferential margins, and said frame being profiled and sealinglyengaging said margins.

13. An anti-flash shutter as defined in claim 3, said plates havingcircumferential margins connected with said frame; and furthercomprising an annular inwardly open member of U-shaped cross-sectionexteriorly embracing said frame and margins and maintaining the latterin tight engagement with the former.

14. An anti-flash shutter as defined in claim 13, said member being ofmetallic material.

15. An anti-flash shutter as defined in claim 13, said member being ofsynthetic plastic material.

16. An anti-flash shutter as defined in claim 13, said member being ofglass-fiber reinforced synthetic plastic material.

7 8 17. An anti-flash shutter as defined in claim 13; and 19. Ananti-flash shutter as defined in claim 3; further further comprising astrap overlying a radial edge face comprising spacing members interposedbetween said of said annular member in taut condition. center plate andthe respective outer plates.

18. An antiflash shutter as defined in claim 3, 20. An anti-flashshutter as defined in claim 3, wherein said compartments are partiallyevacuated to wherein at least one of said plates is a filter for laseran extent requisite for causing concave inward deforbeams.

mation of said outer plates.

1. An anti-flash shutter, comprising a frame having an opening for thepassage of light; first means extending across said opening and defininga chamber; second means also extending across said opening andsubdividing said chamber into one compartment adapted to face the heatflash of a nuclear explosion and subject to destruction by such flash,and an axially successive additional compartment through which lightmust pass after passing through said one compartment; and third meansfor simultaneously terminating the passage of light through both of saidcompartments so that maximum opaquing of the shutter results upon theoccurrence of a flash and opaquing of at least said additionalcompartment remains even in the event of destruction of said onecompartment.
 2. An anti-flash shutter as defined in claim 1, said centerplate having a circumferential margin; and wherein said third means islocated in the region of said margin.
 3. An anti-flash shutter asdefined in claim 1, said first means comprising at least two at leastsubstantially parallel transparent outer plates spaced from one anotherso as to form said chamber, and said second means comprising a centerplate located between said outer plates.
 4. An anti-flash shutter asdefined in claim 1, wherein said third means comprises at least one unitincluding a charge of carbon powder and an explosive adapted todischarge said carbon powder into one of said compartments, and at leastone explosively vaporizable wire adapted to discharge into the other ofsaid compartments and form a reflective layer therein.
 5. An anti-flashshutter as defined in claim 3, said center plate being of a materialhaving high thermal resistance.
 6. An anti-flash shutter as defined inclaim 3, said plates having circumferential margins sealingly connectedwith said frame; and wherein said frame is composed at leastpredominantly of elastomeric material which is resiliently yieldable. 7.An anti-flash shutter as defined in claim 6, wherein said elastomericmaterial is silicone rubber.
 8. An anti-flash shutter as defined inclaim 6, further comprising an electrically conductive additive admixedwith said elastomeric material.
 9. An anti-flash shutter as defined inclaim 8, wherein said additive is graphite.
 10. An anti-flash shutter asdefined in claim 3, wherein said plates are of synthetic plasticmaterial.
 11. An anti-flash shutter as defined in claim 3, said thirdmeans being electrically activatable; and further comprising electricalconductor means and connecting plug means embedded in said frame.
 12. Ananti-flash shutter as defined in claim 3, said plates havingcircumferential margins, and said frame being profiled and sealinglyengaging said margins.
 13. An anti-flash shutter as defined in claim 3,said plates having circumferential margins connected with said frame;and further comprising an annular inwardly open member of U-shapedcross-section exteriorly embracing said frame and margins andmaintaining the latter in tight engagement with the former.
 14. Ananti-flash shutter as defined in claim 13, said member being of metallicmaterial.
 15. An anti-flash shutter as defined in claim 13, said memberbeing of synthetic plastic material.
 16. An anti-flash shutter asdefined in claim 13, said member being of glass-fiber reinforcedsynthetic plastic material.
 17. An anti-flash shutter as defined inclaim 13; and further comprising a strap overlying a radial edge face ofsaid annular member in taut condition.
 18. An anti-flash shutter asdefined in claim 3, wherein said compartments are partially evacuated toan extent requisite for causing concave inward deformation of said outerplates.
 19. An anti-flash shutter as defined in claim 3; furthercomprising spacing members interposed between said center plate and therespective outer plates.
 20. An anti-flash shutter as defined in claim3, wherein at least one of said plates is a filter for laser beams.